Daily Politics and Economics comment. Co-Author of How to Lose a Referendum – the Definitive Story of Why Britain Voted for Brexit [http://bit.ly/2ryynRG]. Economics and Politics teacher in London. 7 years' Independent experience after 4 years in the state sector. Prior to that a management consultant. All opinions here are my own

You may be confused, given the forecast at the moment is for the Labour and Conaervative share of the vote to be similar and the repeated complaints that Labour benefit from our election system, to see the most up-to-date forecasts for the May 7th election. But the growth of the SNP has meant that Labour could well lose a load of seats in constituencies where the number of voters and normal turnout means that can happen without them having lost a load of votes. The four polls released over last weekend suggest that the Tories could be the largest parties by between 13 and 35 seats. What is most interesting however is how impossible it may be for either mainstream party to form a government.

Let’s take the forecast from Peter Kellner of the polling company YouGov. They predict that the Conservatives will have 297 seats, Labour 262, SNP 35 seats (on 4% of the total UK vote), Lib Dems 30 seats, UKIP 4 seats, Greens 1 seat and the others 21.

Given the arithmetic goes like this: Conservatives and SNP have ruled out any type of deal. If you add the Lib a Dems’ 30 seats to the Conservatives’ seats that makes 327, which is a majority of 4. Hardly workable, but looks better when you add the seats that the DUP may win, which ranges from 8 to 10. The DUP may not join a coalition but may offer a confidence and supply arrangement to the Conservatives, which enables the government to get the Queen’s speech and budgets through with a majority of about 30. This is a perfectly plausible arrangement, and could feasibly last the full Parliament. As for Labour, they would need both the Lib Dems and SNP to join them to even make 327, so if this is the result, it is unlikely they would be able to form the government.

However, if Steve Fisher’s forecast for Elections Etc comes true, things look rather different. They predict that the Conservatives will have 285 seats, Labour 279, SNP 40 seats, Lib Dems 30 seats, UKIP 4 seats, Plaid Cymru 3, Greens 1 seat and the others 18. This becomes interesting as Labour plus SNP plus Lib Dems is now 349 seats, which is a comfortable majority of 48 seats. So that means government is possible led by Labour. The Conservatives, however, would have trouble forming a government with anyone if this were the result. The forecast from ‘Election Forecast’ is not much different. Conservatives will have 286 seats, Labour 273, SNP 42 seats, Lib Dems 26 seats, DUP 8, SDLP 3, Plaid Cymru 2, UKIP 1 seats and Greens 1 seat. Once again, Labour, SNP and Lib Dems could have a workable government, but the Tories would have little chance.

As they also wouldn’t with May2015.com’s poll, run by the New Statesman magazine which uses current polling but includes Lord Ashcroft’s recent constituency by constituency polls: Conservatives: 281, Labour: 264, SNP: 55, Lib Dems: 24, Ukip: 3, Greens: 1. Obviously, the most striking feature here is how many seats the SNP will have. Should that happen, we will be worrying a lot more about how destabilised Parliament will be than whether a coalition of working government can be formed.

But going back to the start, it doesn’t look good for Labour in terms of seats. All in all, it doesn’t look good for a stable government either.